Snap switch



Jan- 1952 E. c. WAHLBERG SNAP SWITCH 2 SHEETSSHEET 1 Filed Nov. 16, 1948 ATTORNEY.

Jan. 29, 1952 E. C. WAHLBERG SNAP SWITCH Filed Nov. 16, 1948 2 SHEETS-SHEET 2 INVENTOR. ERIC c. WAHLBERG ATTORNEM Patented Jan. 29, 1952 SNAP SWITCH Eric C. Wahlberg, Stamford, Conn., a'ssignor to Electrolux Corporation, Old Greenwich, Conn., a corporation of Delaware 7 Application November is, 1948, Serial No. so,24s'

' 6 Claims.. (01. 200-437.)

This invention relates to a new type of switching device for the control of electrical apparatus and more particularly embraces improvements in mechanisms for controlling the energization and deenergization of electrical circuits by means of snap action make and break switching devices.

Heretofore, a number of snap action devices for circuit controlling purposes have been devised. Howeven-the usual mechanism suggested for effecting or establishing quick make and break contacts or.such similar circuit control means have been of an excessively complicated structure, or have been such as to necessitate close to tolerances'in their moving parts for eifective operation, or have been adapted for use in only one of a number of preferred positions for positive ease of actuation, and then such actuation is usually possible only by push button control operating in-the direction of motion of the make and break contact alignment.

The present device herein described is an embodiment adapted to overcome these defects of the prior art and to provide varied and other simple economies in switch construction, especially in snap action switching mechanisms.

Further objects include the provision of an efficient and positively acting switching device for use in electrical circuits.

Another object is to provide a snap action switch which is easy to manipulate.

Still another object is to provide a snap switch which operates without necessitating too critical an adjustment of.operating elements.

A further object is to provide an electrical switchwherein a plurality of contact carriers are operated with a snap action type ofresponse by means of a single actuating device, the contacts remaining firmly closed and incapable of. premature opening as by vibration or excessive jarring.

.Theseand other further objects are readily understood'upon reference to the accompanying drawings and description of one embodiment of the invention.

In the drawings:

Figure 1 is a vertical sectional view through an embodiment of the invention, showing a portion from which the cover (see Fig. 2) is removed, partly in plan view; and illustrates a unit wherein a pluralityof make and break contacts are actuated by a single switch operating button;

Figure 2 is a plan view of a cover for the open a side or sides-ofthe switch device of Fig. 1;

Figure 3 is a vertical sectional view of in i contact carrier of the dividually actuatedswit h yp -shownin-r'lgai 2 Figure 4 is a diagrammatical view of one switching device in unactuated position;

Figure 5 shows the switching device of Fig. 4 in a state wherein energyis stored in the flexible spring upon partial actuation;

Figure 6 shows the switch elements, partly in plan view, in position upon complete actuation and completion ofj-the snap action, while the broken line portion shows the relative position of the parts upon'partial release of the actuator;

and

Figure 7 shows the relative position of the parts upon still further release of the actuator with the original contacts reengaged upon completion of the return snapaction just prior'to the position shown in Fig. 5; 7

Referring now more particularly to the accompanying drawi 's,";the preferred embodiment shown is adapte' for use in operating circuits for various electrical devices, control means, and the like. A suitably hollow! moulded base structure I 0 is provided with slots and grooves for holding the various switch elements, while a pair of a corner or lateral covers H serve to make a dust tight unit of the assembled switch. I

- The switch elements include a contact carrying element 20 of flexible resilient spring-like material having a fixed end 2| which is rigidly held in a groove l3 cut in base l0, and a movable end 22 provided with contacts 23 and 24. The contact carrier 20 is biased towards the position in which its inner contact 23 engages an; axial contact 25 on center post 26. Lugs 2la formed from the body 2| of the fixed end of contact carrier 20 hold the contact carrier securely in groove l3.

Leaf spring 30 has slots or apertures 32, 34 out near the ends thereof, 32 for placement over a tongue 21 formed at the free end of contact carrier 20, and slot .34 for placement over a guide member 40 aflixed in'anactuat'or 4i. Spring 30, as shown, is provided with a hook-shaped or bent end portion 3 Iwhich serves as a fulcrum or bearing surface, riding against the lower surface of actuator 4 I However, where a hard bearing surface is provided on thelower surface of actuator 4|, a sharply bent end flange with its free end contacting this surface may be used in place of fulcrum 3| and type of structure will likewise serve as a rocker or fulcrum for spring 30.

In the actuation of this. switch, spring 30 at first undergoes a compression or ilexing and sub- .held in rolling com" ressional contact-against the lower surface of actuator 4|. Pin 40 serves to hold the end 3| of spring 30 substantially in oriented and aligned position while the other end (near slot 32) of spring 30 is free to move laterally, taking contact carrier 20 with it, whereupon the contact carrier is snapped into position placing contact 24 into engagement against outer contact 28 on outer contact carrier supporting post 29.

The switch unit is assembled by placing actuator 4| in position in the top of the switch base molding l0, button 42 being inserted into a bushing 43 so that a pin 44 projecting from button'42 slides in a groove 45 cut in bushing id-topreventv actuator 4| from turning. Thenthe. center post 26, contact carriers 20, and the outer contactcarrier supports 29 are placed into their respective openings and grooves, such as' l3, cut in the molded base It. Finally, leaf sprin 30,-;somexwhat preformed and U-shaped, is compressed into position by mounting slots 32 and 34 thereof over and between tongue 21 and pin 40, respectively. In this position spring 30 exerts a slight vertical pressure against the contact'carrier 20 whereby the latter is held and maintained firmly in positionagainst center contact 25 regardless of any slight shocks, jolts, etc., to which the switch may be subjected-in use.

In order to operate the switch,.button 42 is de-- pressed, whereupon increased compression of spring 30 is effected and energy stored therein. Stillfurther compression of spring 30 causesthe latter to flare outwardly (end 3! being fixed-by pin 40) and through its bearing arrangement on tongue 2], spring 30 carries the'free end 22 of thrusting or snapping of the contact carrier 211 to the posiiton disclosed in Fig. 6. Although the spring 30 has been illustrated as U-shaped in configuration, it will be obvious that a helical spring, disposed to produce the force required counter to the bias of thecontact carrier, would also eifect the desired action.

Applicant, however, is not to be held strictly to any theoretical explanation of the action of this embodiment of his invention; the accompanyin theory of its operation is added simply to facilitate an understanding thereof.

It may be true in the-initial stages-of its. operation that the hooked end. 3|v of spring 30 will roll on the surface of actuator 4| and (neglecting any reaction with post 40$ increase the contact Pressure between elements 23 and -but this is eifected only momentarily and during the very first portion of the downward travel of actuator 4|. In fact, it is just this added contact pressure which assures the triggering of the snap action and the production of a force tending to cause a separating movement terminating in the reestablishment of the equilibrium condition shown inFig. 6 wherein the free end 32 ofspring has moved laterally and outwardly until. contact is established. between elements. 24 and 28 where,--

upon further outward extension of the free end of spring 30 is arrested.

Thus, the vertical movement of actuator 4| effectively imparts a horizontal component of force to the free end 22 of contact spring 20, producing a snap action type of response. It is to be noted that when the outward flaring tendency of spring 30 under compression causes'the freely bearinged end of spring 30 to'be thrown outwardly, it simultaneously efiects a rocking action of U-shaped leaf spring 30 on its fulcrumed end 3|. Thus, the. direction of application of any stored compression force is transformed into a force having aicomponentJ-exerted. at right angles to the directionofmovementof actuator 4|. Moreover, as soon as'contact carrier 20 is carried the slightest distance outwardly from the vertical axis of fulcrum 3| by the initial outwardly flaring action of spring 30, the entire unit is snapped into a new contact-making position wherein contact element 24-= comes t rest against contact 28.

The operation of the switching device is more readily understood by analyzing its actionwith the aid of a. number of relatively continuous steps, see Figs. 4, 5, 6, and 7. Thus, depression of actuator 41 compressesspring 30. At flrstthis.

compressiontendsto-maintain the contacts already biased torclosingm sition in more firmly. clos dcontact and axis. 50. is shortened to that. shown'at 150,,Fig, 5. Then slightl ater. com.--

pzession tends-tmovercome the lateral and. inwardlv biasingzcomnonent of spring20. by estaba-oomppnent-of force outward from. the axis,- .-counter. to the ;.;bias of: contact. carrier: 20, andeat riehtengles: to the-direction of actuation otmemberdl .dneto the=flexing of. the springafl.

superposes oil-inwardly biased spring. 20'an.

opposite or.---connteractin force which arises from the outwardly flaring. action (above explained) of the free end of spring 30 upon further compression.-of:-.menrber- 4|. Since end 3| of spring-3|] is-substantially fixed, this flaring force isaimparted 'aszahorizontal force-to movable end 22 of contacttcarrier'ni Thus, movable end 22 is carried outwards-with a; snap action accompanied by arslight rotation of spring 30, on fulcrum-3|, i. e. a rocking ofspring 30 on fulcrum 3|. Thus the compression of spring 30 causes the spring30 to snapout at its free end in a-horizontal directionwitli' still further rocking on fulcrum 3 has-shown in Fig. 6, the axis now-assuming-the position shown at 250 slightly elongated tact carrier 20 is snapped back into its initial, position against contact'25, 7. In this case,

spring30 is rolled back on fulcrum 3| by the biasing action of spring contact member 20 which I exerts aforcereturning itself and spring 30 towards the center axis-of theswitching device; Once: a ainiwhen: the free end 22 of contact carrier 20 liesidirectlyunderthe vertical axis '450, Fig. 7'.-. .oi-.fulcrum point. 31,.anyenergy of compres iohmemaining-stored-in-springu holds contact carrier 20 firmly in positiontwithcontacts.

23 and 25 in engagement as originally described. The final release of the actuator 4| allows axis 450 of Fig. 7 .to elongate, returning to its original size 50, Fig. 4. It is an advantageous feature of this type of action that a plurality of contact carriers 20 can be actuatedsimultaneously and each contact carrier is individually forced into and out of contact with its correspondingly associated fixed contact points by means of its own individually associated spring 30. ..Such an action insures the makin and breaking of each contact individually. No one contact is compressed more or less than any other contact but is actuated into its respective position by its own individual spring 30. Thus each make and break contact is under a pressure which is independent of any previous or subsequent spring action or of any other simultaneously and operatively actuated contact. Moreover, the type of response herein effected is unique in that a vertically applied actuating force is first stored and subsequently converted into a lateral component of force in a novel manner. The compression of a single spring effects both the conversion in direction as well as the snap action response of the switching means.

The portion of the contact carriers extending below base l provide terminals 52, 53 to which the operating circuits to be controlled by the switch are connected.

The mechanism of the switch embodied in this invention is capable of numerous applications. As shown, it is adapted for manual operation. However, it maybe used with automatic machinery, limit switching devices, included in various electrical control circuits, and the like. It is to be noted that any number of such independently operated switching members may be arranged around a single actuator or plunger as shown in the figures and that each switching element is independently actuated by utilizing a minimum number of intermediate moving parts. Moreover, the contact elements are self-biased and returned to their original positions upon release of the actuating means.

It is to be understood that the examples of the invention herein described are merely preferred embodiments thereof, and that various changes may be made therein without departing from the scope of this invention which is to be limited solely by the scope of the appended claims.

What I claim is:

1. An electric switch comprising a contact carrier movable back and forth between two circuit making positions and having a free end movable about a fixed end, means for biasing the contact carrier to one of said positions, an endwise flexed and compressible resilient spring, one of its ends engaging said free end of the contact carrier and disposed upon actuation to produce a force counter to the biasing means upon the contact carrier, an actuator engaging the other end of the spring and efiective upon actuation to move the spring in a direction substantially in line with the contact carrier and' to flex the spring, whereby the contact carrier is caused to move from one to the other of said two circuit making positions.

2. A snap action electric switch comprising a contact carrier movable back and forth between two circuit making positions and having a free end movable about a. fixed end, means for biasing the contact carrier to one of said positions, an endwise flexed and compressible resilient U- shaped leaf spring, one of its ends engaging said free end of the contact carrier. and disposed'upon actuation to produce a force counter to the bias-. ing means upon the contact carrier, an actuator engaging the other end of the leaf spring, and having a projection engaging a recess in said. other endof the leaf spring for maintaining said U-shaped leaf .spring in a substantially fixed orientation, and substantially against movement in a plane perpendicular to the direction of movement of said actuator, and effective upon actuation to'move the spring in a direction substantiallyiniline with the contact carrier and to flex the leaf spring, whereby the contact carrier is caused to move in snap action response from one to the other of said two circuit making positions. 3. A snap action electric switch comprising a contact carrier movable back and forth between two circuit making positions and having a free end movable about a fixed end, means for biasing the contact carrier to one of said positions, an endwise flexed and compressible resilient U- shaped leaf spring, one of its ends engaging said free end of the contact carrier and disposed upon actuation to produce a force counter to the biasing meansupon the contact carrier, an actuator engaging the other end of the leaf spring, and having a projection engaging a recess in said other end of the leaf spring for maintaining said U-shaped leaf spring in a substantially fixed orientation, and substantially against movement in a plane perpendicular to the direction of movement of said actuator, and effective upon actuation to move the spring in a direction substantially in line with the contact carrier and to flex the leaf spring, whereby energy of actuation is stored in the flexed leaf spring and subsequently released to cause the contact carrier to move in snap action response from one to the other of said positions.

4. A snap action electric switch comprising a contact carrier movable back and forth between two positions and having a free end movable about a fixed end, means for biasing the contact carrier to one of said positions, an endwise flexed and compressible resilient U-shaped leaf spring, one of its ends engaging said free end of the contact carrier and disposed upon actuation to produce a force counter to the biasing means upon the contact carrier, a movable actuator having a projection engaging a recess in the other end of the leaf spring for restraining said other end against movement in a plane perpendicular to the direction of movement of said actuator, and said actuator being arranged to apply pressure at right angles to the direction of motion of said contact carrier and counter to the biasing means upon said contact carrier, whereby the contact carrier is caused to move in snap action response from one to the other of said two positions,- said U-shaped leaf spring being maintained in a substantially fixed orientation.

5. A snap action electric switch comprising a contact carrier movable back and forth between two positions and having a free end movable about a fixed end, means for biasing the contact carrier to one of said positions, an actuator for said switch, and a flexed and compressible resilemeamse substantially where said leaf spring. bears on said actuator forrestraining said other end. against movementina plane perpendicular to the direction of movement. of said actuator, the actuator being airanged to apply pressure at right angles to the direction of motion of said contact carrier and counter to the biasing means: upon said contact. eanier, whereby operation of said actuator flexes the leaf spring to cause. the contact carrier to; move in. snap action response vfrom one to the other. of said positions, said. U-shaped leaf spring heme-maintained in a substantially fixed 011-. entatiom 6. A snap action electric switch comprising a. contact carrier movable back and tenth between two positions and having a free and movable about'afixed end, means for biasing, the contact carrier to one of said positions, an flexed end compressible resilient. U-shaped leaf spring.

one of its ends engaging said free'end oi the conttact carrier and disposed upon. actuation to produce a force counter to the biasing means upon a. recess .inthe other emLof the leaf spring-for" said other end; against movementiin a plane perpenoiculax to the: directional movement of said actuator, and effective upon paxtial. actuationto flex the leaf springimdmamtainflie contact earner insaid one position, saith aotnator adapted upon. further operation to, move the ina dnwection substantially iniine' with the contactcarxier and to tnrtherfiex the leaf spring to: cause the contact carrier to move: in snap action response. iron the one to the other: of saictpositionsann tomaintain thercontaotcamtie: in said other position, U-shaped lea! spring being'main'tained a. substantially fixed.

orientation.

. ERIC 0. WAHLBERG.

REFERENCES The following of-record in the? file of patent:

I UNITED STATES PATENTS L 4 the contact carrier, and arranged to mamiain Number Name said oontact carrier in one of said positions. a 501,450 Stanley July 11, 1893 movable actuator having a. projection engaging 25 2.237.705 Am: 85. 1941 

